1. Field of the Invention
The present invention relates in general to data processing systems and, in particular, to a data processing system and method including a server and client computer system coupled together utilizing a local area network. Still more particularly, the present invention relates to a data processing system and method including a server and client computer system coupled together utilizing a local area network for remotely controlling execution of a processor utilizing the processor's built-in test access port for debugging the execution of the processor.
2. Description of the Related Art
Personal computer systems are well known in the art. They have attained widespread use for providing computer power to many segments of today's modern society. Personal computers (PCs) may be defined as a desktop, floor standing, or portable microcomputer that includes a system unit having a central processing unit (CPU) and associated volatile and non-volatile memory, including random access memory (RAM) and basic input/output system read only memory (BIOS ROM), a system monitor, a keyboard, one or more flexible diskette drives, a CD-ROM drive, a fixed disk storage drive (also known as a "hard drive"), a pointing device such as a mouse, and an optional network interface adapter. One of the distinguishing characteristics of these systems is the use of a motherboard or system planar to electrically connect these components together. Examples of such personal computer systems are IBM's PC series, Aptiva series, and Thinkpad series.
With PCs being increasingly connected into networks to allow transfers of data among computers to occur, more operations such as maintenance, updating of applications, and data collections are occurring over the network. Computer networks are also becoming essential to their user. It is desirable minimize loss of productivity by increasing availability of network resources.
For code development and problem resolution, the ability to read/write registers in a processor and to set break points is essential. The first tools were In Circuit Emulators which replaced the processor under test with early processors such as the 8086 and 8088. External bus snoopers were created for the 386 and 486 family of processors. The Pentium family of processors have built-in debugging tools which are accessed via a test access port (TAP). The TAP complies with the IEEE 1149.1 (JTAG) test architecture standard.
One prior solution to testing execution of a processor was to add a connector to the planar to allow access to the processor included on the planar. The planar under test was then attached via a ribbon cable to a computer having a TAP adapter interface and application software.
This solution has the disadvantage of significant added cost. Although the cost of a single connector may only be $0.50, the added cost for mass producing one million computer systems with this solution is $500,000.
Another disadvantage is that the system and developer must be in close proximity. The debug cable can only drive a length of three feet. Thus, the developer and system under test must be physically close together, i.e. within three feet. Yet another disadvantage is the requirement that a master system exist for each client system. Typically this requires a debug station to be time-shared due to cost considerations. In addition, the developer may only test a single system at a time.
Therefore a need exists for a data processing system and method for remotely controlling and debugging execution of a processor utilizing the processor's built-in test access port without significant additional cost.